Method of and tank for storing oil



1,559,016 s. L. STOVALL' METHOD OF'AND TANK FOR STORINGDIL Oct. 27, 1925- Filed Jan. 1921 WITNESS ig 2 I INVENTOR X/JW 5L- 5TOVALL' ATTORNEYS Patented Oct. 27, 1925.

UNITED STATES PATENT. OFFICE. I

SMITH L. STOVALL, OF KERTO, CALIFORNIA, ASSIGNOR TO U. A. GIBSON AND J. F.

' GIBSON, JR., BOTH OF VISALIA, CALIFORNIA.

METHOD OF AND TANK FOR STORING OIL.

Application filed January 4, 1921.

To all whom it may concern:

Be it known that I, SMITH L. S'rovALL, a citizen of the United States, and a resident of Kerto, Kern County, State of California, have invented a certain new and useful Method of and Tank for Storing Oil, of which the following is a specification.

The invention relates to tanks for storing or containing crude oil or oil products.

At the present time it is the practice to store crude oil and oil products in tanks, which are provided with roofs, preferably steel roofs, which are gas tight and which are secured to the sides of the tank in a gas tight manner. These tanks are vented to preclude the accumulation of pressure in the tank due to the introduction of oil into the tank or the evaporation of the oil or the lighter constituents thereof in the tank. The vent usually consists of a pipe of large diameter secured to the tank adjacent the -top, extending downward to the ground and led off some 7 5 feet from the tank, where its open end is covered with several thicknesses of fine wire gauze. As the oil in the tank evaporates or volatilizes, the gas produced passes out through the pipe, and the space in the tank above the oil is filled with pure gas, which is not explosive. When oil is drawn from the tank, however, or when the atmospheric temperature falls, air is drawn into the tank through the vent pipe, producing an ideal explosive mixture there1n,wh ch is a serious fire hazard, since the exploslve mixture may be readily i ited by a static discharge or by other in uences. It is essential that the vent pipe be left open, otherwise the withdrawal of the oil or the condensation of the gas due to temperature drop, would cause a condition of vacuum which would cause the tank to collapse.

An. object of my invention is to provide an oil storage tank in which this fire and explosion hazard is practically eliminated. At practically all ordinary atmospheric temperatures, there is a largeamount of evaporation or volatization of the hghter constituents of the oil and the research departments of the United States Government have estimated that the loss due to evaporation of the oils in storage alone, in the United States, is in excess of $125,000,000 or year. The investigations of the research departments have been carried on almost entirely with reference to the large storage Serial No. 435,013.

tanks, and as far as I am aware, no investigatlons have been made to determlne the losses due to evaporation and volatization of the oils before they reach these large stor age tanks. The custom in the oil fields is to flow the oil from the well through a flume, in which much of the sand is settled out,- then into a large tank wherein water and more sand is settled out and then into a gauging tank where-it is held for a day. These two tanks are known as flow tanks, and the loss of the lighter constituents of the oils in these tanks by evaporation or volatization, is very great. The lighter constituents lost by evaporation or. volatization are of very high gravity, probably around 80 Baum, and comprise the more valuable constituents of the oil.

Another object of my invention is to greatly. reduce the amount of the lighter constituents of the oil which are lost by evaporation or volatizat-ion.

The invention possesses other advantageous features, some of which, with the foregoing, will be set forth at length in the following description, where I shall outline in 1 full, that form of the invention which I have selected for illustration in the drawings accompanying and forming part of the present specification. In said drawings, I have shown one embodiment of my invention, but it is to be understood that I do'not limitmyself to such form, since the invention as set forth in the claim, may be embodied in a pluralityof forms.

Referring to-said drawings:

Figure 1 is a vertical section through an oil tank embodying my invention.

Figure 2 is a detail of a portion of the roof structure on a larger scale.

In accordance with my invention, I reduce the accumulation of gas in the storage tank and conserve the gas produced, so that the loss by evaporation or volatization is minimized; I prevent the mixture of air with the gas, so that an explosive mixture is not produced and I greatly reduce the exposed area of the oil, making fire very easy to combat. The invention is applicable to tanks of any size from small tanks up to the largest storage tanks, 'which at the present time are oil in the tank and raises and lowers with the oil in the tank. The partition is impervious and is preferably made of sheet.

The partition is suitably braced, so that it The buoyant partition will retain its shape. 2 is formed with a depending circumferential flange 4, which forms a chamber 5 below the partition in which the liberated gases accumulate, and with an upstanding circumferential flange 6 which renders the partitionbuoyant when there is no accumulation of gas in the chamber 5, in which instance the level of the oil is above the horizontal partition, but not above the upper edge of the flange 6. In practice, the flanges 4 and 6 are preferably integral, consisting of a sheet of metal secured intermediate its edges to the partition. lVhen desired, the chamber within the upper flange and above the partition may be filled with water to a depth of several inches, to act as a heat insulator against abrupt changes in atmospheric temperature.

Means may be provided for discharging the accumulated gases from the chamber 5, when a predetermined accumulation forms therein. For this purpose, the partition is provided with a discharge pipe 8 to which is secured a flexible conduit 9, through which the gas is conveyed to a permanent conduit for further disposal, such as conveyance to ,a cooling or condensing plant.. The discharge of gas through the pipe is controlled by a valve 12, which is controlled by variation in the accumulation of gas in the chamber. Connected to the valve 12 is a float 13, which operates to open the valve when the distance between the partition and the oil level in the chamber reaches a predetermined maximum. The valve shown is of the sliding gate type, but it is to be understood that any suitable-type of valve may be used for this purpose.

The tank may be provided with a fixed roof 14, when desired, to prevent rain from entering the tank, and this roof is reterably spaced from the sides of the tan or is adequately ventilated to prevent the accumulation of any leakage gas therein.

By providing a floating or buoyant roof or partition, which floats on the surface of the oil, the explosion and fire hazard is greatly reduced because no explosive mixture is produced, since no air is admitted to the tank. The gas thus remains pure and can be compressed or condensed to produce a very high gravity product which may be mixed with gasoline to improve its quality. The enormous losses of this high gravity constituent are also reduced to a minimum. The oil is introduced into and withdrawn from the tank through a conduit or conduits placed below the partition and preferably adjacent or in the bottom of the tank.

I claim:

The combination with a tank for containing oil or oil products, of a vertically movable partition in said tank, a depending peripheral wall on said partition forming a chamber below the partition for the accumulation of gas, a gas discharge conduit on said partition, a valve for controlling the flow of gas through saidconduit and means operative by variation in the amount of gas in said chamber, for opening and closing said valve.

In testimony whereof, I have hereunto set my hand.

SMITH L. STOVALL. 

